An uninterruptible power supply system disclosed in Japanese Patent Laying-Open No. 2011-72068 (Patent Document 1) includes a plurality of uninterruptible power supply devices, a switching circuit switching to a bypass power supply with outage in case of failure of each uninterruptible power supply device, and a switch opening/closing an output of the switching circuit. The uninterruptible power supply system disclosed in Patent Document 1 is configured such that connection between the switching circuit and a load can be selected by the switch to select a configuration in which one uninterruptible power supply device is connected, or a configuration in which the plurality of uninterruptible power supply devices are connected in parallel.
Thus, even when one of the uninterruptible power supply devices fails, the uninterruptible power supply system disclosed in Patent Document 1 can supply power in a short time, and thus can lower the risk of deactivation of the load due to an outage of the bypass power supply within a time required to repair the uninterruptible power supply device.